Kabbalah su Genesi 25:21

Rabbi Yehuda continued with the verse, "And Isaac entreated Hashem for his wife" (Gen. 25:21). What is the meaning of "entreated?" That he offered a sacrifice and prayed for her. What offering did he sacrifice? A burnt offering. He sacrificed by studying the verses "and Hashem was entreated of him" (Ibid.), and "So Hashem was entreated for the land" (II Shmuel 24:25). There it means that a sacrifice has been offered, here too it means, a sacrifice has been offered. It is written, "And Isaac entreated," "and Hashem was entreated", a celestial fire that came to meet the lower fire.

Rabbi Acha bar Jacob, said, Come and behold. It is written, "And Isaac entreated Hashem for his wife, because she was barren" (Gen. 25:21). Rabbi Acha asks, Why is she barren? Because the Evil Inclination does not have its full strength in the world, the only fruition and multiplying comes through prayer. It is then written, "and Hashem was entreated by him, and Rivkah his wife conceived." Once the Evil Inclination is aroused, there is procreation!